//获取后缀名的方法
exports.getMime = function (extname) {
    switch (extname) {
        case ".html":
            return "text/html; charset=utf-8";
        case ".css":
            return "text/css; charset=utf-8";
        case ".js":
            return "text/javascript; charset=utf-8";

        case ".png":
            return "image/png";

        case ".PNG":
            return "text/png";

        case ".jpg":
            return "text/jpg";

        case ".JPG":
            return "text/jpg";
        default:
            return "text/html; charset=utf-8";
    }
}